The world’s two biggest sources of greenhouse gas emissions announced plans Tuesday to clean up their economies and aggressively develop low-carbon energy sources to better fight climate change.

China on Tuesday formally presented its plans to curb greenhouse gas emissions by 2030 in preparation for the big United Nations climate summit in Paris later this year. If met, the targets, coming from the world’s largest source of greenhouse gases, would seem to give the planet a fighting chance to avert the worst impacts of climate change later in this century.

Also on Tuesday, U.S. President Barack Obama announced plans to work more closely on climate issues with Brazil, including effectively tripling the amount of renewable energy like wind and solar power in the United States by 2030. Brazil announced similar targets. The United States has already committed to reducing emissions by about 28 percent by 2025.

In addition to capping emissions, China said it would aggressively develop nuclear power and renewable energy, limit unchecked industrial growth, and implement market-based schemes to tackle carbon pollution. Beijing’s climate objectives build on previously announced plans to throttle back reliance on dirty fuels like coal and boost clean energy, part of a rebalancing of the Chinese economy to escape the environmental ravages of decades of breakneck growth. China’s new green hue is especially significant ahead of the Paris summit: Chinese intransigence was the principal cause of the near-total breakdown of the last big climate confab in Copenhagen in 2009.

For decades, global climate policy has been bedeviled by divisions between rich countries, historically responsible for the bulk of carbon in the atmosphere, and developing countries, which got started late on industrialization but are among the top polluters today.

China’s new approach to climate talks doesn’t erase that chasm entirely, but it does seek to straddle the divide, and that makes some sort of global accord in Paris more likely. China’s proposal still speaks of different responsibilities for developing countries, but also acknowledges the country’s pressing obligation to take serious action to limit its own contribution to the problem. The green push is driven both by the country’s own need to promote “sustainable development” and “by its sense of responsibility to fully engage in global governance,” said China’s climate submission, known as an Intended Nationally Determined Contribution.

“This is a clear sign that we’re moving past the old developed-developing country divide to a new understanding that all major economies have to contribute their fair share to the global effort,” Bob Perciasepe, president of the Center for Climate and Energy solutions, a nonprofit, said in a statement.

Chinese officials, hewing to a tactic of under-promising and over-delivering, said they would make every effort to cap greenhouse gas emissions even before the headline target of 2030. The formal submission also pledges the country’s “best efforts to peak early.” Researchers at the London School of Economics recently concluded that China could indeed meet its environmental goals sooner than expected, because the green push is a political imperative for China’s leaders and because the economic rebalancing seems to be proceeding faster than expected.

The combination of climate commitments from countries such as China, the United States, Russia, Japan, and members of the European Union alone won’t be enough to limit global temperature increases to 2 degrees Celsius by the end of the century, the world’s official red line for global warming. But an extra effort to promote low-carbon energy sources, like natural gas, and more efficient use of coal in major economies could be enough to meet those climate targets, the International Energy Agency noted this month.

Another thing that might help is more climate action by other large emitters, especially India and Brazil. India has so far vowed to prioritize economic development, including a fresh embrace of coal for the power sector, over concerns about climate change, though the country also has high hopes for solar power. Brazil on Tuesday committed to double its use of renewable energy and protect huge chunks of forest. It has yet to submit its climate pledge but promised an “ambitious” target ahead of the Paris talks.